This invention relates to a device for cleaning and polishing an optical fiber, and more particularly to a device for cleaning and polishing the end of an optical fiber either after the fiber and its surrounding cable have been installed in a connector, or after resin treatment (i.e., encapsulation) of the fiber.
The use of fiber optic cable as the transmission medium for information has become increasingly prevalent. Fiber optic cable has a number of advantages over the well-known electrical wire transmission schemes, such as coaxial cable for video signals or twisted-pair wiring for data transmission. Included among the advantages are low-loss, low-cost, high-bandwidth, transmission security and a larger number of data paths per circular area of the transmission medium. The low-loss characteristic allows data to be transmitted over greater distances before the signal must be amplified by "booster" equipment. Perhaps the biggest advantage of fiber optic cables over electrical wire, though, is the higher integrity of the transmitted information due to the immunity of the fiber optic cable from electromagnetic interference.
Notwithstanding the foregoing, fiber optic cable is not without its disadvantages. For example, due to the relatively small diameter of the "core" portion of the optical fiber strand (e.g., on the order of eight microns for a single mode fiber) within the cable, it is critical that, at a junction or interface between the ends of two fiber optic cables, the transmission axis (i.e., the core) of each optical fiber strand be in precise alignment with one another. This is to ensure that all of the light energy propagating within the core of one strand is transferred to the core of the other strand.
Further, due to the small diameter size of the optical fiber strand (which is defined herein to mean the inner core portion together with its surrounding cladding portion), the fiber strand is normally encased in an outer protective cable of relatively much larger diameter. For example, a single mode fiber has an inner core portion of optically pure glass of a diameter of 8 microns, surrounded by a cladding portion of less pure glass of a diameter of 125 microns. Surrounding the cladding may be several outer concentric layers, including a silicone coating surrounding the cladding, followed by a buffer jacket. Next may be a concentric layer of strength members, followed by an outer polyurethane jacket. All of the outer concentric layers following the cladding are referred to hereinafter collectively as the "outer cable". The diameter of the outer cable may approach 4.5 mm. The outer cable aids in the handling of the fiber and also prevents the fiber from bending at too sharp of an angle, which could cause breakage of the fiber.
At the termination point of the cable (e.g., at a piece of "repeater" equipment that increases or "boosts" the amplitude of the optical signal), the cable is held in place in a receptacle on one side of a mechanical connector. The connector may be mounted to a panel of the housing of the booster equipment. A second fiber optic cable may be held in place in a receptacle located on the opposite side of the connector. The optical axis of each strand and corresponding outer fiber optic cable are in alignment with one another at an interface point. Alternatively, a light source or receiver may be located on the opposite side of the connector for interface with the fiber optic cable.
However, the interface between the ends of the two optical fiber strands is susceptible to fine dirt and dust particles and grease with the result that the exposed end of one or both optical fiber strands may become contaminated. This occurs when the interface is exposed to the atmosphere for any reason (e.g., when connecting or disconnecting the cables). This could lead to a possible severe degradation in the amount of light energy transferred between the fiber strands. In such case, it is known to disassemble the fiber optic cable from the corresponding coupling of the mechanical connector and clean the end of the fiber cable with an appropriate cleaning device and associated solution. However, such disassembly is impractical and oftentimes unfeasible, given the nature of the connector and its associated equipment.
In the prior art, it is known to insert a rod or a swab, saturated with a cleaning solution, into a receptacle in a connector in an attempt to clean the optical fiber strand. However, such attempts were not always successful because the rod or swab did not always wipe through the center of the optical fiber strand. However, such conventional method may suffice for cleaning other portions of the end surface of the cable.
Heretofore, no known method and means exist for effective cleaning and polishing the end of the optical fiber strand while the strand and corresponding fiber optic cable are held in the connector.
Accordingly, it is a principal object of the invention to provide a device for cleaning the end surface of an optical fiber strand surrounded by an outer fiber optic cable and mounted in the connector without first disassembling the cable from the connector.
It is a general object of the invention to provide a device for quickly and efficiently cleaning the end surface of an optical fiber strand mounted in a connector.
It is a further object of the invention to provide a device for polishing and/or cleaning the end of an optical fiber strand mounted in a connector.
It is a still further object of the invention to provide a device for polishing the end of an optical fiber strand prior to insertion of the fiber in a connector.
The above and other objects and advantages of this invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings.